Power and Signal Distribution

7.2.3 Optional Energy Star Compliant PSUs

Energy Star 4.0 (80-Plus, Bronze-compliant) active-PFC power supply units are available as an option for these systems. The specifications of the high-efficiency power supplies match those of the standard units except for the following aspects:

■Efficiency: no less than 82 percent efficient at 20 or 100 percent of rated load and no less than 85 percent efficient at 50 percent of rated load (at 115 VAC/60 Hz and at 230 VAC/60 Hz input.

■Power factor of greater than 0.9 measured at full rated load at 115 VAC/60 Hz and at 230 VAC/60 Hz input

7.3Power Control

The generation of +3, +5, and +12 VDC is controlled digitally with the PS On signal. When the PS On signal is asserted, all DC voltages are produced. When PS On is de-asserted, only auxiliary power (+5 AUX) is generated. The +5 AUX voltage is always produced as long as the system is connected to a live AC source.

7.3.1 Power Button

The PS On signal is typically controlled through the Power Button which, when pressed and released, applies a negative (grounding) pulse to the power control logic on the system board. The resultant action of pressing the power button depends on the state and mode of the system at that time and is described as follows:

 

 

Table 7-3.

 

 

 

Power Button Actions

 

 

 

 

 

 

System State

Pressed Power Button Results In:

 

 

Off

Negative pulse, of which the falling edge results in power control logic

 

 

 

asserting PS On signal to Power Supply Assembly, which then initializes. ACPI

 

 

 

four-second counter is not active.

 

 

 

 

 

 

On, ACPI Disabled

Negative pulse, of which the falling edge causes power control logic to

 

 

 

de-assert the PS On signal. ACPI four-second counter is not active.

 

 

 

 

 

 

On, ACPI Enabled

Pressed and Released Under Four Seconds:

 

 

 

Negative pulse, of which the falling edge causes power control logic to

 

 

 

generate SMI-, set a bit in the SMI source register, set a bit for button status,

 

 

 

and start four-second counter. Software should clear the button status bit within

 

 

 

four seconds and the Suspend state is entered. If the status bit is not cleared by

 

 

 

software in four seconds PS On is de-asserted and the power supply assembly

 

 

 

shuts down (this operation is meant as a guard if the OS is hung).

 

 

 

Pressed and Held At least Four Seconds Before Release:

 

 

 

If the button is held in for at least four seconds and then released, PS On is

 

 

 

negated, de-activating the power supply.

 

 

 

 

 

 

7-4

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Technical Reference Guide